New nationwide survey reveals teens interact with strangers on the Web

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This teen thought that she was already being smart just by setting her online profile to "private." A new online friend, "19-year-old Matt" shows her otherwise. "Matt" turned out to be Det. Frank Dannahey, who was illustrating online dangers to teens and their parents.

Dateline wires the home of a volunteer, Jenny, from top to bottom with hidden cameras. Then she called repairmen to her house for a simple problem we created as a test with Jenny's pool. NBC's Chris Hansen reports.